General procedure for the synthesis of 2-fluoro-5-bromopyridine and pinacol ester of bisboronic acid from 2-fluoro-5-bromopyridine and pinacol ester of bisboronic acid: under nitrogen protection, Pd(dppf)Cl2 (4.16 g, 5.68 mmol) was added in a single step to a solution containing 5-bromo-2-fluoro-pyridine (10 g, 56.82 mmol), pinacol ester of bisboronic acid (21.64 g, 85.23 mmol) and potassium acetate (16.73 g, 170.46 mmol) in a solution of dioxane (100 mL). The mixture was stirred at room temperature for 10 minutes and then heated to reflux for 6 hours. Upon completion of the reaction, the solvent was removed by direct evaporation and the residue was purified by flash silica gel column chromatography to afford the target product 2-fluoropyridine-5-boronic acid pinacol ester (10.5 g, 82.85% yield). The structure of the product was confirmed by 1H NMR (400 MHz, chloroform-d): δ 8.59 (s, 1H), 8.15 (dt, J = 1.76, 8.41 Hz, 1H), 6.91 (dd, J = 2.26, 8.28 Hz, 1H), 1.35 (s, 12H).
